poster - International Conference of Agricultural Engineering

characteristics resulting from of genetic factors as well as the management procedures of the
nursery (SILVA, 1998).
One of managements applied during hardening implies the application of water stress
to acclimate the plants to field conditions. According Stape et al. (2001) the survival and
development of seedlings in the field depend on the interactions between the morphological /
physiological attributes and the environmental components of the site. The
morphological/physiological attributes are more important under harsh field conditions.
Acclimatization involves morphological, physiological and nutritional changes which
reflect the efficiency of water use and, consequently, the plant's ability to resist adverse
conditions, especially in the early post-planting. Coopman et al. (2008) reported that
morphological changes allow the plants to maintain the balance between transpiration and
absorption and increase the capacity to generate new roots.
Morphological changes induced by water stress in seedlings were also studied by
several authors who observed the reduction in shoot biomass, root and total (SILVA, 1998;
COOPMAN et al, 2008), reduction in height (REIS et al., 1988, OLIVA et al., 1989;
COOPMAN et al, 2008) and diameter (REIS et al., 1988), changes in the root / shoot
(LANDSBERG & MYERS, 1989), reduction in the number of branches (COSTA E SILVA et
al., 2004), number of leaves (Olive et al., 1989) and the leaf area (Stoneman et al. 1994
LEMCOFF et al., 1997 and Silva, 1998; COOPMAN, et al., 2008; reduction of root growth
(MCKERSIE & Ya'acov, 1994; COSTA E SILVA et al., 2004), an increase in the ratio dry
weight / fresh weight (LI 1998).
This study aimed to verify the morphological responses of Eucalyptus grandis
seedlings when subjected to different levels of water stress during hardening.
2. Material and methods
The study was conducted in the Nursery Forestry Seedling Research, Faculty of
Agronomic Sciences of UNESP, Botucatu, Sao Paulo – Brazil, located at the coordinates 22
º 51'22'' south latitude and 48 ° 26'0'' West longitude, at an altitude of 810m and I Cwa type
climate, Köppen classification of Wilhelm and average annual rainfall of 1524 mm.
The seeds of Eucalyptus grandis were from a clonal seed orchard. The tubes used had
55 cm ³ volumetric capacity and the substrate was a commercial product based on
decomposed pine bark and expanded vermiculite with the following characteristics: 29.2%
macropores, 46.8% micropores and 76.0% total porosity, retention of 2.2 g water/g of dry
substrate.
Two fertilization via subirrigation were carried out, one on the 35 th day after sowing
(DAS) with ammonium nitrate and potassium nitrate at a concentration of 400 and 316 mg L -1
of N and K respectively, and the other at 54 DAS, with Peters ® fertilizer (20:10:20) at a dose
of 2 g L -1 .
During the 70 th to 100 th DAS, the seedlings had different water managements. T1
seedlings without suffering water stress or permanently subirrigated, T2, T3, T4 and T5
seedlings irrigated when reaching a tension of water retention at the substrate of -50, -
100, -500 and -1500 kPa, respectively, measured by gravimetric method.
The morphological characteristics evaluated were height, stem diameter, leaf area,
shoot dry mass, roots dry mass and leaf specific weight.
The statistical design was completely randomized, with five treatments with four
replications (trays) of 48 seedlings, which were considered useful for the morphological